__author__ = 'Apple'
import time

def leave_hms(time_string):
    that_time = time.strptime(time_string, '%Y-%m-%d %H:%M:%S')
    return time.strftime('%Y-%m-%d', that_time)


if __name__ == '__main__':
    print leave_hms("2015-6-30 21:12:31")